Pope Francis is urging people to speak out against persecution of Christians, whom he likened to the Church’s first martyrs.

His denunciation of discrimination suffered by Christians came a day after three Christmas day bombings targeted Christians in Iraq.

Francis didn’t cite any countries in his remarks to tourists and pilgrims in St. Peter’s Square as the church Thursday recalled its first martyr, St. Stephen. Francis said unfortunately more Christians are suffering discrimination and violence now than in Christianity’s early times. He said some countries guarantee human rights “on paper” but not in practice, leaving Christians subject to “limitations and discrimination.”

Francis said “injustice must be denounced and eliminated.”

Christians have been attacked in parts of Africa and the Middle East, and in some places cannot worship openly.